Tread member and endless tracks made therefrom

ABSTRACT

A one-piece molded plastic tread segment adapted for coupling with an identical tread segment without distortion of either member which comprises a one-piece body portion having a recessed opening defined by integral walls and adapted to receive the teeth of a driving means, said body portion having extending from either end thereof a plurality of tongue members, the area between any two tongue members defining a clevis area adapted to receive the tongue members of another identical member, each tongue member having an aperture molded therein and extending completely therethrough in a transverse direction, the configuration of the aperture of two of the tongue members, each of which is located at the extremities of and on opposite sides of the body portion, being such as to conform with the cross section of a pin, said cross section of said pin being substantially elliptical, said aperture in said tongue member being disposed such that it forms a predetermined angle phi along its major axis in relation to the horizontal plane of the body portion, the configuration of the apertures of the remaining or inner tongue members being substantially triangular such that a certain degree of rotational freedom is permitted said pin when inserted through said apertures. Endless tracks produced by the cooperative engagement of a plurality of tread members are especially suited for use on tracked vehicles, such as for example, snowmobiles.

United States Patent Primary Examiner-Richard J. Johnson Attorney-Robert A. Gerlach et al.

Persin Oct. 24, 1972 [54] TREAD MEMBER AND ENDLESS [57] ABSTRACT TRACKS MADE THEREFROM A one-piece molded plastic tread segment adapted for [72] Inventor: William J. Persin, Coraopolis, Pa. coupling with an identical tread segment without distortion of either member which comprises a one- [73] Asslgnee' g zf Corporatlon New York piece body portion having a recessed opening defined by integral walls and adapted to receive the teeth of a [22] Filed: June 25, 1971 driving means, said body portion having extending from either end thereof a plurality of tongue members,

[.21] Appl' 156:7. the area between any two tongue members defining a clevis area adapted to receive the tongue members of [52] US. Cl ..305/38 another identical member, each tongue member hav- [51] Int. Cl. ..B62d 55/22 ing an aperture molded therein and extending [58] Field of Search.....305/ 35 R, 36, S0, 38; 74/251, 1 completely therethrough in a transverse direction, the

74/254 configuration of the aperture of two of the tongue members, each of which is located at the extremities [56] References Cited of and on opposite sides of the body portion, being such as to conform with the cross section of a pin, said UNITED STATES PATENTS cross section of said pin being substantially elliptical,

599,970 3/1898 Menk ..74/254 x said aperture in said tongue member being disposed 976,664 11/1910 Laubenstein ..74/2s4 Such that it forms a predetermined angle along its 1,629,755 5/1927 Wilmot ..74/254 major axis in relation to horizontal Plane of the 3,602,364 8/1971 Maglio .305/35 R body P the configuration of the apertures of 3,628,834 12/1971 Anderson ..305/35 R remaining or inner tongue members being substan- 3,646,752 3/1972 Kampfer ..74/250c tially triangular such that a certain degree of rotational freedom is permitted said pin when inserted through said apertures. Endless tracks produced by the cooperative engagement of a plurality of tread members are especially suited for use on tracked vehicles, such as for example, snowmobiles.

8 Claims, 7 Drawing Figures Patented Oct. 24, 1972 3,700,281

3 Sheets-Sheet 1 lll k l llVl/E/VTOR. P5117 I III I\ [h Patented Oct. 24, 1972 3,700,287

3 Sheets-Sheet 5 I AM /V709.

ATTORNEV.

TREAD MEMBER AND ENDLESS TRACKS MADE THEREFROM This invention relates to a tread member construction and more particularly to read members which may be connected to other identical tread members to form endless tracks which tracks are particularly suited for use on tracked vehicles, such as, for example, a snowmobile.

It has been heretofore known to construct endless chains from individual link members utilizing pin connectors to fasten the tongue portion of one link member between the clevis portions of an adjacent link. Such endless chains have generally been formed of metal and as a result, the pins were subject to wear and failure especially when the chains were adapted as tread members on tracked vehicles such as snowmobiles and the like. Although the abrasive effects may be minimized by frequent cleaning and lubrication or by providing seals which both retain lubricating fluid and exclude foreign matter, such means are both time-consuming and expensive. Thus in tracked vehicles, such as snowmobiles, it has long been customary to employ unitary endless flexible belts made or rubber and fabric. Such unitary belts have not proven entirely satisfactory since .wear in any one part of the belt necessitates replacement of the entire belt, which is also both time-consuming and costly. Furthermore, unitary belts do not permit adjustment of the belt to different lengths to compensate for elastic deformations.

It is therefore an object of this invention to provide a tread member and an endless track comprised of a plurality of said tread members devoid of the foregoing disadvantages. Another object of this invention is to provide reinforced tread members having a high relative strength per unit weight. A further object of this invention is to provide endless tracks of multiple tread members which are easily assembled and disassembled. Still. another object of this invention is to provide endless tracks composed of easily replaceable tread members. Yet a further object of this invention is to provide endless tracks of easily replaceable tread members such that the endless track may be readily adjusted to any desired length. It is still another object of this invention to provide an endless track in which disengagement of the individual tread members cannot occur while the track is in normal operation. It is still a further object of this invention to provide tread members made from metal reinforced plastic. An additional object of this invention is to provide an endless track comprised of a plurality of interconnected reinforced plastic tread members, which endless track is particularly well suited for use on tracked vehicles such as, for example, a snowmobile and the like.

The foregoing objects and others which will become apparent from the following description and the accompanying drawings in which:

FIG. I is a partial plan view of two interconnected link members of the invention,

FIG. II is an end view of the interconnected link members of FIG. I,

FIG. III is a partial end view of two adjacent tread members in the position requisite for insertion or removal of the connecting pin,

FIG. IV is a plan view of a preferred tread segment,

FIG. V is a section of the tread member of FIG. IV showing the placement of the metal reinforcement,

FIG. VI is an elevation view of the endless track in engagement with a preferred driving means, and

FIG. VII is a side view, partially in section, of a snowmobile having an endless track formed of tread memrecessed opening defined by integral walls and adapted to receive a driving means, the body portion having a plurality of tongue members extending from each end thereof, the area between two tongue members defining a clevis area, such that the tongue members of another identical tread segment are received in the clevis area when the two tread members are brought into horizontal alignment, the tongue members having apertures molded therein such that when the tongue members of one tread are positioned in the clevis area of an adjacent read, a pin may be inserted through the apertures thus forming a hinged connection between the two tread segments. Thus, the invention contemplates endless tracks particularly adapted for use on tracked vehicles wherein a plurality of tread members are joined in cooperative relationship to form a continuous track.

Referring more particularly to the drawings wherein the same reference character or numeral refers to like or corresponding parts throughout the several views, FIG. IV illustrates a tread member constructed in accordance with the principles of this invention as a onepiece molded plastic tread member 1, comprising a body portion 2 and tongue portions 3 and 3a and a clevis area 4 defined by the tongue portions 3 and 3a. The tread member 1, may be molded of any suitable thermoplastic resin, and more particularly, an abrasion resistant thermoplastic resin, in a manner well known to those skilled in the art. In the preferred embodiment shown in FIG. IV, the body portion 2, is provided with a recessed opening 5 defined by integral walls 6, 7, 8 and 9 said recessed opening 5, being adapted to receive the teeth of a suitable driving means, such as, for example, sprocket teeth. The tongue members 3 and 3a are formed integral with the body portion 2, and contain transverse apertures 10 and 10a, molded therein. In the practice of this invention, the tread members can be molded so as to contain any number of tongue members 3. For ease of illustration, however, the invention will be described by reference to an embodiment as shown in FIG. I where a tread member having a minimum number of tongue portions is illustrated.

FIG. I illustrates two tread members 1 integrally connected by means of a pin 12, inserted through the apertures 10 and 10a, of the tongue members 3 and 3a respectively. As shown in FIG. II, the pin 12, has a cross section equivalent to a rectangle with the addition of two semicircular ends. It is to be understood, however, that the cross section of the pin 12, may be ovular or elliptical and would function equally as well according to the invention. The body portion 2, is provided with two tongue members 3a, one of which is positioned on one extremity of the body portion 2 and the other of which is positioned on the other extremity and the opposite sides of the body portion 2. Each of the tongue members 3a contains an aperture a extending in a transverse direction therethrough, of an area of substantially the same shape as that of the cross section of the pin 12. The tongue member 3 contains an aperture) extending in a transverse direction therethrough, the aperture 10 having a triangular area asshown in FIG. II of such dimension so as to permit a predetermined degree of rotational freedom of the pin 12 after the latter has been inserted.

The aperture 10a of tongue member 3a is disposed such that when the body portion 2 lies in a horizontal plane, a predetermined angle (b is formed between the major axis of the aperture 10a and the horizontal plane as shown in FIG. II. As shown in FIG. III, two tread members 1, are aligned such that the angle between the body portions 2, is 2 relative each to the other. This position is the only position in which the pin 12, can be either inserted or withdrawn. The pin 12, is inserted through the aperture 10a such that the pin 12, is completely clear of tongue member 3a and has sufficient freedom to relocate itself in the triangular apertures 10 of the tongue members 3.

Thus the pin 12 is disposed in the apertures 10 and cannot be withdrawn through the aperture 10a so long as some tension is maintained across the hinge joint. So long as tension is maintained there will be an inter-. ference or mismatch between the ends of the pin 12 and the aperture 10a which effectively prevents lateral movement of the pin 12 and provides a positive entrapment of the pin 12 thus assuring that the tread members I, will not become separated.

The pin 12 may be made of any suitable material such as for example, metal, rubber, plastic or the like so long as it possesses the requisite degree of structural strength, which of course is dependent on the intended use of the link members or the endless belts made therefrom.

Each tread member together with identical tread members may thus be joined into an endless track of any desired size by engaging the tongue members of one tread member into the clevis portion of an adjoining member and inserting the pin as described hereinabove. It is also readily apparent that disassembly of the adjacent tread members can be readily accomplished by a reversal of the above described procedure. However, the only condition under which the pin may be removed is when the combination of tension load across any two tread members is reduced to zero and relative angular displacement between the tread members is 2 4).

In order for the tread members to be suitable for use on tracked vehicles it is essential that the molded plastic of which they are to be constructed be provided with suitable reinforcement. The reinforcement is preferably metal and-most preferably steel of about 26 gauge. The reinforcement is formed from a metal blank and shaped so as to approximately conform to the configuration of the tread segment. FIG. V is illustrative of the manner in which the reinforcement is disposed in the tread segment. A metal reinforcement blank 14, is formed to substantially conform with the outer configuration of the track segment 1. The reinforcement 14 is then encased in plastic 15, by suitable molding means in a manner well known to those skilled in the art.

An endless track composed of pin-connected reinforced molded plastic track segments is especially suitable for use in conjunction with a driving means such as a sprocket wheel. In such an embodiment as shown in FIG. VI a plurality of tread members connected in an endless track is shown traversing a sprocket wheel 16, of a drivingmeans 17 connected to a driving source of any conventional construction (not shown). The construction of the tread segments of this invention permits the assembled tread segments to pull direction and assures good flexibility and low bending stresses when traversing rough terrain. This also enables the pins to withstand the cyclic and concentrated bending loads that are applied to the track when traveling over the drive and idler sprockets. To further minimize undesirable reverse pivoting and provide greater track stability, the track segments of the invention provide flexure only in one direction, i.e., only in the direction illustrated in FIG. III.

The endless track of tread segments made possible by this invention are particularly suitable for use as endless tracks on tracked vehicles, such as, for example, snowmobiles and the like. When employed in such vehicles, it is necessary that the molded tread member be constructed of an abrasion resistant thermoplastic having sufficient stiffness to prevent substantial deformation of the link-members and also that the molded tread be provided with a metal reinforcement over which the plastic material is molded.

A plastic material which is well suited for this application is a thermoplastic polyester based polyurethane elastomer such as, for example, TEXIN elastomer as manufactured by the Mobay Chemical Company. Other suitable elastomeric polyurethanes are those disclosed in for example, U.S. Pat. Nos. 2,729,618 and 3,2l4,4l 1. It is to be recognized, however, that though a tread member molded of polyurethane is preferred it is also possible to employ other suitable thermoplastic molding materials, such as, for example, polycarbonates, polyurethanepolycarbonate blends and the like. Furthermore, in those applications where less strenuous uses are to be made of the endless track the tread members need not be metal reinforced and may be molded of any suitable plastic material of sufficient stiffness to prevent any substantial deformation during operation.

In FIG. VII is depicted an endless track of tread members of the invention in the preferred embodiment wherein the endless track is employed on a tracked vehicle, and in particular on a snowmobile. A snowmobile 18 of conventional construction having a conventional power source (not shown) and driving means comprising sprocket wheels 19, sprocket teeth 20 and bogie wheels 21 is equipped with an endless track 22 of adjoining link members 1, of this invention. The endless track 22, of the invention is particularly suitable for use in snowmobiles or the like where the ease of replacement of damaged link members and the ease of assembly of endless tracks of any desired length is particularly desirable. Furthermore, the endless tracks have a high relative strength per unit weight, thereby permitting more efficient operation of the snowmobile. The novel pin connecting means provided by this invention prevents unintentional disengagement of the tread members during operation while permitting easy disassembly and replacement of individual tread members in the event of damage.

While there has been described herein, a tread member and endless tracks made therefrom adapted primarily for use with tracked vehicles, it is to be understood that the tread members may be employed to form endless tracksadapted for any use in any heretofore known operation requiring the use of endless tracks.

Additionally it is to be understood that the driving means described as suitable herein is merely a preferred embodiment of the invention and that the track segments and endless belts made therefrom may be modified so as to function with any other suitable driving means known to the art.

It is to be further understood that many substitutions or alterations in the components and conditions mentioned as suitable herein may be made by one skilled in the art and though the invention is described in considerable detail in the foregoing such detail is solely for the purpose of illustration and that variations may be made by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is l. A one-piece molded plastic tread segment adapted for coupling with an identical tread segment without distortion of either member which comprises a onepiece body portion having a recessed opening defined by integral walls and adapted to receive the teeth of a driving means, said body portion having extending from either end thereof a plurality of tongue members, the area between any two tongue members defining a clevis area adapted to receive the tongue members of another identical member, each tongue member having an aperture molded therein and extending completely therethrough in a transverse direction, the configuration of the aperture of two of the tongue members, each of which is located at the extremities of and on opposite sides of the body portion, being such as to conform with the cross section of a pin, said cross section of said pin being substantially elliptical, said aperture in said tongue member being disposed such that it forms a predetermined angle (it along its major axis in relation to the horizontal plane of the body portion, the configuration of the aperture of the remaining or inner tongue members being substantially triangular such that a certain degree of rotational freedom is permitted said pin when inserted through said apertures.

2. The one-piece molded plastic tread member of claim 1 wherein the tread member is a molded thermoplastic polyurethane tread member.

3. The one-piece molded plastic tread of claim 2 wherein the polyurethane is molded around a metal reinforcement, the metal reinforcement having a configuration substantially the same as the outer configuration of the molded plastic tread member.

4. The one-piece molded plastic tread member of claim 3 wherein the metal reinforcement is formed from a blank of 26 gauge steel.

5. The one-piece molded plastic link member of claim 1 wherein the tongue portions of one tread segments are disposed in the clevis portion of a second track member, the two track members being rotated so as to subtend an angle of 2 inserting a pin through the apertures of the tongue members such that the pin is completely clear of the aperture of the tongue member located at the extremity of the body portion, such that the pin is seated in the triangular apertures of the inner tongue members in a manner such that disengagement of the two track members is prevented while permitting partial rotating relationship of adjoining track members when in normal operating relationship.

6. An endless track comprising releasably interconnected adjoining tread segments of claim 5.

7. In a tracked vehicle driven by the action of an endless track around a driving means, the improvement comprising employing as the endless track, the endless track of claim 6.

8. The tracked vehicle of claim 7 wherein the tracked vehicle is a snowmobile. 

1. A one-piece molded plastic tread segment adapted for coupling with an identical tread segment without distortion of either member which comprises a one-piece body portion having a recessed opening defined by integral walls and adapted to receive the teeth of a driving means, said body portion having extending from either end thereof a plurality of tongue members, the area between any two tongue members defining a clevis area adapted to receive the tongue members of another identical member, each tongue member having an aperture molded therein and extending completely therethrough in a transverse direction, the configuration of the aperture of two of the tongue members, each of which is located at the extremities of and on opposite sides of the body portion, being such as to conform with the cross section of a pin, said cross section of said pin being substantially elliptical, said aperture in said tongue member being disposed such that it forms a predetermined angle phi along its major axis in relation to the horizontal plane of the body portion, the configuration of the aperture of the remaining or inner tongue members being substantially triangular such that a certain degree of rotational freedom is permitted said pin when inserted through said apertures.
 2. The one-piece molded plastic tread member of claim 1 wherein the tread member is a molded thermoplastic polyurethane tread member.
 3. The one-piece molded plastic tread of claim 2 wherein the polyurethane is molded around a metal reinforcement, the metal reinforcement having a configuration substantially the same as the outer configuration of the molded plastic tread member.
 4. The one-piece molded plastic tread member of claim 3 wherein the metal reinforcement is formed from a blank of 26 gauge steel.
 5. The one-piece molded plastic link member of claim 1 wherein the tongue portions of one tread segments are disposed in the clevis portion of a second track member, the two track members being rotated so as to subtend an angle of 2 phi , inserting a pin through the apertures of the tongue members such that the pin is completely clear of the aperture of the tongue member located at the extremity of the body portion, such that the pin is seated in the triangular apertures of the inner tongue members in a manner such that disengagement of the two track members is prevented while permitting partial rotating relationship of adjoining track members when in normal operating relationship.
 6. An endless track comprising releasably interconnected adjoining tread segments of claim
 5. 7. In a tracked vehicle driven by the action of an endless track around a driving Means, the improvement comprising employing as the endless track, the endless track of claim
 6. 8. The tracked vehicle of claim 7 wherein the tracked vehicle is a snowmobile. 